Ok, let's start with this:
$(function () {
var citiesByState = {
NJ: ["Trenton", "Newark", "Hackensack"],
NY: ["Albany", "NYC", "Niagara"],
PA: ["Philly", "Pittsburgh", "Harrisburg"]
}
$('select[name=state]').change(function () {
var cities = citiesByState[$(this).val()];
var opts = $.map(cities, function(name) {
return "<option>" + name + "</option>";
});
$('select[name=city]').html(opts.join(""));
});
});
Let us know if you have questions.